Modeling plasma instability with electric arc discharges

[Colin LeMahieu]

I was reading a paper recently about guiding electric arc discharges with lasers. http://loa.ensta-paristech.fr/ilm/uploads/ILM/134_Forestier_discharge_AIPAdvances_2_012151_2012.pdf

Since electric arcs are plasmas and they seem to be stabilized by lasers, could the same principle be applied to fusion plasma?

 

[Astronuc]

I was reading a paper recently about guiding electric arc discharges with lasers. http://loa.ensta-paristech.fr/ilm/uploads/ILM/134_Forestier_discharge_AIPAdvances_2_012151_2012.pdf

Since electric arcs are plasmas and they seem to be stabilized by lasers, could the same principle be applied to fusion plasma?

With a quick read of the article, it appears the interest is inducing a more controlled atmospheric discharge, i.e., lightning, such that greater protection of electrical infrastructure is achieved. The Earth's atmosphere is many orders of magnitude greater density than a fusion plasma. It's not clear the advantage of this process for magnetically confined fusion systems. Perhaps the_wolfman can provide some insight.

 

[Colin LeMahieu]

Interesting. I could see how lower density could affect results. Is the lower density because of technical limits to confinement? Higher density would generally be desired if possible, right?

 

[Astronuc]

Interesting. I could see how lower density could affect results. Is the lower density because of technical limits to confinement? Higher density would generally be desired if possible, right?

The pressure of the plasma is a function of particle density, n, and the temperature, T, by virtue of P = nkT, where k is the Boltzmann constant.

http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/idegas.html#c1

The plasma pressure is limited by the magnetic pressure and the structural materials confining the plasma. Higher density would be desirable, but we are constrained by the limits on materials.

 

[the_wolfman]

I was reading a paper recently about guiding electric arc discharges with lasers. http://loa.ensta-paristech.fr/ilm/uploads/ILM/134_Forestier_discharge_AIPAdvances_2_012151_2012.pdf

Since electric arcs are plasmas and they seem to be stabilized by lasers, could the same principle be applied to fusion plasma?

The laser pulse creates a partially ionized of column of gas that has a reduced density. These two effects reduce the breakdown voltage and resistivity is the column. Current takes the path of least resistance, so the laser pulse is creating a preferred path for the arc to follow.

Magnetically confined plasmas are usually completely ionized. So its hard to imagine where this mechanism would be applicable except maybe during start up.

It is interesting thato the arcs have such a well defined cylindrical shape.

 

[mheslep]

As far as I know, field strength is a limitation with magnetic confinement fusion plasmas, but not structural limits of materials, not yet.